1. Field of the Invention
The present invention relates to a permutation or interconnecting network for simultaneous selective connection of each of N inputs to an individual output of N outputs.
2. Description of the Related Art
Interconnecting networks are required for example when a plurality of signal sources are to be connected individually by line or physically to an equal number of users. Interconnecting networks should generally be blockage-free, i.e. the connection of any input to any output does not block the possibility of connecting any other input with any other output. Furthermore, it is often required that interconnecting networks can easily be expanded as regards the number of their inputs and outputs. For economy reasons interconnecting networks should have as few switches as possible.
A typical interconnecting network is the crossbar switch. Although it can easily be expanded it requires a very great number, that is N.sup.2 switches. The interconnecting network which best fulfills the above conditions so far is the Benes network: it is blockage-free. It contains only a minimum of stages and switches, that is N.multidot.logN-N/2 switches. Because of its self-similarity it can be modularly extended. It has low meshing between the stages (i.e. few line intersections) and this is advantageous from the constructional point of view.
The Benes network consists of two mirror-symmetrical baseline networks. The baseline network is known and in addition will be briefly explained below. Since for reasons of the working speed the switches of the interconnection networks consist in many uses of semiconductor devices, such as transistors, the two mirror-symmetrical baseline networks of the Benes system are usually constructionally different. For purposes of the description and claims, the term "network of Baseline configuration" and the term "baseline network" are defined as a network of the form illustrated in FIG. 5.7 (a) at page 338 of the text Computer Architecture and Parallel Processing, K. Hwang & F. A. Briggs, Mc Graw Hill International Editions, Computer Science Series (1984). A network as defined is also illustrated in Wu & Feng, On a class of Multistage Interconnection Networks, IEEE Transactions on Computers, Volume C-29, No. 8, page 109, FIG. 3 (August, 1980).